Goose in farm building disturbed Alec (8)
I believe the answer is:
barnacle
'goose' is the definition.
(barnacle is a kind of goose)
'farm building disturbed alec' is the wordplay.
'farm building' becomes 'barn' (barn is a kind of farm building).
'disturbed' is an anagram indicator.
'alec' anagrammed gives 'acle'.
'barn'+'acle'='BARNACLE'
'in' is the link.
(Other definitions for barnacle that I've seen before include "Sea creature - lean crab (anag)" , "'Marine crustacean, attaches to a boat-hull (8)'" , "Be carnal consuming this shellfish" , "Marine crustacean (attaching to rocks, ships etc.)" , "Marine crustacean - European goose" .)