From casual survey appear fat (4,5)
I believe the answer is:
look round
'from casual survey' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.
'appear fat' is the wordplay.
'appear' becomes 'look' (synonyms).
'fat' becomes 'round' (round can mean fat or plump).
'look'+'round'='LOOK-ROUND'
Can you help me to learn more?
(Other definitions for look round that I've seen before include "The Globe should do this" , "inspection" .)