Fashion - cost not excessive (8)
I believe the answer is:
moderate
'not excessive' is the definition.
(I've seen this in another clue)
'fashion cost' is the wordplay.
'fashion' becomes 'mode' (synonyms).
'cost' becomes 'rate' (rate is a kind of cost).
'mode'+'rate'='MODERATE'
(Other definitions for moderate that I've seen before include "Not extreme - not very good" , "Become less extreme" , "(Keep) within reasonable limits" , "Not excessively right- or left-wing" , "Average; not radical" .)