Vulgar bloke pinching primate's bottom (5)
I believe the answer is:
cheap
'vulgar' is the definition.
(synonyms)
'bloke pinching primate's bottom' is the wordplay.
'bloke' becomes 'chap' (both can mean a man).
'pinching' is an insertion indicator (taking inside).
'bottom' suggests the final letters.
The last letter of 'primate' is 'e'.
'chap' enclosing 'e' is 'CHEAP'.
(Other definitions for cheap that I've seen before include "not doing much damage" , "Tawdry - inexpensive" , "A snip" , "Inexpensive or tastelessy showy" , "good value" .)