Lacking room, spearmint moved for sage (7)
I believe the answer is:
sapient
'for sage' is the definition.
(I've seen this in another clue)
'lacking room spearmint moved' is the wordplay.
'lacking' is a deletion indicator.
'room' becomes 'rm' (abbreviation).
'moved' indicates anagramming the letters.
'spearmint' with 'rm' taken away is 'speaint'.
'speaint' anagrammed gives 'SAPIENT'.
(Other definitions for sapient that I've seen before include "of great wisdom" , "Snipe at, being wise" , "very keen" , "Literary word for wise" , "Discerning" .)