Zip back low plush jacket (5)
I believe the answer is:
oomph
'zip' is the definition.
(I've seen this in another clue)
'back low plush jacket' is the wordplay.
'back' says the letters should be written backwards.
'low' becomes 'moo' (both can mean to make a cow noise).
'jacket' suggests removing the centre (the letters worn by the word as a 'jacket' are use).
'plush' with its centre taken out is 'ph'.
'moo' in reverse letter order is 'oom'.
'oom'+'ph'='OOMPH'
(Other definitions for oomph that I've seen before include "Vitality, zing" , "Dynamism" , "drive" , "Sexy, exciting quality" , "Go" .)