Turn up on time in position (3)
I believe the answer is:
put
'position' is the definition.
(I know that position can be written as put)
'turn up on time' is the wordplay.
'turn' says the letters should be written in reverse.
'up on' becomes 'up' (similar in meaning).
'time' becomes 't' (abbreviation).
'up' back-to-front is 'pu'.
'pu'+'t'='PUT'
'in' is the link.
(Other definitions for put that I've seen before include "Set (in place)" , "Place; placed" , "Place in a location" , "Place in a position" , "Place, lay" .)