Small pale creature (4)
I believe the answer is:
swan
'creature' is the definition.
(swan is a kind of creature)
'small pale' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'pale' becomes 'wan' (synonyms).
's'+'wan'='SWAN'
(Other definitions for swan that I've seen before include "Graceful bird" , "possibly mute" , "Large, long-necked bird" , "Kind of song, in the end" , "Large aquatic bird" .)