Manage to encircle small thicket (5)
I believe the answer is:
'thicket' is the definition.
'manage to encircle small' is the wordplay.
'manage' becomes 'cope' (synonyms).
'to encircle' means one lot of letters goes inside another.
'small' becomes 's' (abbreviation - e.g. clothes size).
'cope' placed around 's' is 'COPSE'.
(Other definitions for copse that I've seen before include "Small group of trees" , "Coppice" , "Dense growth of shrubs or trees" , "Wood - thicket" , "Harvested woodland" .)