Spicy, oddly prim fashion designer (7)
I believe the answer is:
piquant
'spicy' is the definition.
(synonyms)
'oddly prim fashion designer' is the wordplay.
'oddly' means one should take alternating letters (letters in the odd-numbered positions are used).
'fashion designer' becomes 'quant' (I've seen this before).
The alternate letters of 'prim' are 'pi'.
'pi'+'quant'='PIQUANT'
(Other definitions for piquant that I've seen before include "Pleasantly sharp in taste" , "Pleasantly pungent, stimulating" , "Flavoursome" , "Having a pungent taste" , "Appetising, tangy" .)