Eat sparingly with a company in part of a muster? (7)
I believe the answer is:
peacock
'part of a muster?' is the definition.
(muster is the collective noun for peacocks)
'eat sparingly with a company' is the wordplay.
'eat sparingly' becomes 'peck'.
'with' is an insertion indicator.
'company' becomes 'co' (abbreviation).
'a'+'co'='aco'
'peck' placed around 'aco' is 'PEACOCK'.
'in' is the link.
(Other definitions for peacock that I've seen before include "It has very long tail feathers that have iridescent eye-like markings" , "Bird noted for showy plumage" , "Blue-green" , "vain person" , "Bird with showy tail" .)