Check greeting in fashionable section (7)
I believe the answer is:
inhibit
'check' is the definition.
(inhibiting is a kind of checking)
'greeting in fashionable section' is the wordplay.
'greeting' becomes 'hi' (hi is a kind of greeting).
'in' means one lot of letters goes inside another.
'fashionable' becomes 'in' (in can mean fashionable or trendy).
'section' becomes 'bit' (both can mean part).
'in'+'bit'='inbit'
'hi' going inside 'inbit' is 'INHIBIT'.
(Other definitions for inhibit that I've seen before include "Prevent expression of" , "Repress" , "Constrain" , "Limit the range or extent of" , "Hold back" .)