Following a trend to a certain extent (5,1,7)
I believe the answer is:
after a fashion
'to a certain extent' is the definition.
(I've seen this before)
'following a trend' is the wordplay.
'following' becomes 'after' (I've seen this before).
'trend' becomes 'fashion' (fashion is a kind of trend).
'after'+'a'+'fashion'='AFTER A FASHION'
(Other definitions for after a fashion that I've seen before include "In some manner but not very well" , "Lady shopping may be" , "like many boutique shoppers?" , "Like a trendy shopper" , "contrive to be not that well" .)