Make bigger space, having left gear out (7)
I believe the answer is:
enlarge
'make bigger' is the definition.
(I've seen this before)
'space having left gear out' is the wordplay.
'space' becomes 'en' (in printing, a space as wide as a letter 'n').
'having' means one lot of letters go next to another.
'left' becomes 'l' (common abbreviation).
'out' indicates an anagram (out can mean wrong or inaccurate).
'gear' anagrammed gives 'arge'.
'en'+'l'+'arge'='ENLARGE'
(Other definitions for enlarge that I've seen before include "Lengthen" , "Amplify" , "Grow" , "swell?" , "Make big" .)