Difficult retreating in rich silk city (8)
I believe the answer is:
ticklish
'difficult' is the definition.
('ticklish' can be similar in meaning to 'difficult')
'retreating in rich silk city' is the wordplay.
'retreating' shows that the letters should be reversed in order.
'in' says the answer is hidden in the clue.
'hsilkcit' is hidden in the letters of 'rich silk city'.
'hsilkcit' backwards is 'TICKLISH'.
(Other definitions for ticklish that I've seen before include "easy to get to laugh?" , "Prone to responding to 1 across" , "Sensitive, needing delicate handling" , "Like a sensitive soul, so to speak" , "(Of a problem) difficult to handle and requiring great tact" .)