*Top (5)

'top' is the definition.
(both can mean to surpass or beat)
This is the entire clue.
(Other definitions for outdo that I've seen before include "Perform better than, be superior to" , "Perform better than another" , "Best" , "Surpass - overshadow - excel" , "Get the better of" .)
'top' is the definition.
(similar in meaning)
This is the entire clue.
(Other definitions for upper that I've seen before include "Higher; part of boot" , "Higher in status" , "Amphetamine pill" , "Higher-ranking" , "Top of shoe; stimulant" .)
(Other definitions for notch that I've seen before include "Nick - incision" , "Mark indented in wood etc" , "Dent" , "Incision on an edge" , "small score?" .)
(Other definitions for tube that I've seen before include "Pack of toothpaste; type of train" , "channel" , "Pipe or hose" , "Cylindrical hollow conduit" , "train network" .)
'top' is the definition.
(I know that head is a type of top)
This is the entire clue.
(Other definitions for head that I've seen before include "''and still the wonder grew / That one small ... could carry all he knew'' (Goldsmith)" , "Leader; front" , "Skull" , "Leader; promontory" , "Leader; water pressure" .)
'top' is the definition.
(apex is a top or peak)
This is the entire clue.
(Other definitions for apex that I've seen before include "climax" , "reasonable fare" , "Top, peak" , "Tip -- top" , "crown" .)
'top' is the definition.
(associated in meaning)
This is all the clue.
(Other definitions for best that I've seen before include "unbeatable" , "The most talented" , "Cream of the crop" , "George -, footballer" , "Most advantageous" .)
'top' is the definition.
(both can mean to beat or outdo)
This is the entire clue.
(Other definitions for cap that I've seen before include "Outdo; brimless hat" , "Soft hat; lid" , "Beat; upper limit" , "Soft headgear" , "Stopper" .)
(Other definitions for ten that I've seen before include "Five times two" , "Half a score" , "How many" , "Roman numeral X" , "Very young" .)
'top' is the definition.
(I know that top can be written as summit)
This is the entire clue.
(Other definitions for summit that I've seen before include "Highest point of a mountain" , "Topmost point" , "Top of a mountain, or meeting between heads of government" , "A high-level meeting?" , "Highest point (of hill)" .)