Entire? With gap (5)
I believe the answer is:
whole
'entire?' is the definition.
(similar in meaning)
'with gap' is the wordplay.
'with' becomes 'w' (abbreviation).
'gap' becomes 'hole' (hole is a kind of gap).
'w'+'hole'='WHOLE'
(Other definitions for whole that I've seen before include "undamaged" , "Integral" , "In entirety" , "Entire, undivided" , "Complete, containing all the parts" .)