Dog organisation in Channel Islands (5)
I believe the answer is:
corgi
'dog' is the definition.
(I know that corgi is a type of dog)
'organisation in channel islands' is the wordplay.
'organisation' becomes 'org' (common abbreviation).
'in' means one lot of letters goes inside another.
'channel islands' becomes 'CI'.
'org' put inside 'ci' is 'CORGI'.
(Other definitions for corgi that I've seen before include "Cardigan, possibly" , "HM's favourite dog" , "Queen's dog?" , "Dog at Buckingham Palace" , "Welsh 11" .)