Closed island, trapping fine gander (6)
I believe the answer is:
shufti
'gander' is the definition.
(I've seen this before)
'closed island trapping fine' is the wordplay.
'closed' becomes 'shut' ('shut' is associated in meaning with 'closed').
'island' becomes 'i'.
'trapping' means one lot of letters goes inside another.
'fine' becomes 'f' (abbreviation).
'shut'+'i'='shuti'
'shuti' placed around 'f' is 'SHUFTI'.
(Other definitions for shufti that I've seen before include "Quick inspection" , "Informally, a brief inspection or look" , "Quick look (colloq.)" , "Peep (from the Arabic)" , "A quick look around, military term" .)