Object having watery shelled egg (5)
I believe the answer is:
thing
'object' is the definition.
(an object is a thing or item)
'watery shelled egg' is the wordplay.
'watery' becomes 'thin' (similar in meaning).
'shelled' indicates the central letters (the outer letters or shell are removed).
The central letter of 'egg' is 'g'.
'thin'+'g'='THING'
'having' acts as a link.
(Other definitions for thing that I've seen before include "Night (anag)" , "See 1" , "An unnamed object or item" , "Individual unit" , "Body" .)