Identify granny in street, standing still (8)
I believe the answer is:
stagnant
'standing still' is the definition.
(I've seen this before)
'identify granny in street' is the wordplay.
'identify' becomes 'tag' (I've seen this in other clues).
'granny' becomes 'nan'.
'in' means one lot of letters goes inside another.
'street' becomes 'st' (abbreviation).
'tag'+'nan'='tagnan'
'tagnan' placed within 'st' is 'STAGNANT'.
(Other definitions for stagnant that I've seen before include "Stale - motionless" , "hardly moving" , "Unmoving (water)" , "(Of water) motionless" , "Brackish and foul" .)