Fur ball seemingly swallowed by moggy (4)
I believe the answer is:
coat
'fur' is the definition.
(an animal's coat)
'ball seemingly swallowed by moggy' is the wordplay.
'ball seemingly' becomes 'o' (O looks like a ball. I am not sure about the 'seemingly' bit.).
'swallowed by' is an insertion indicator.
'moggy' becomes 'cat' (I've seen this before).
'o' inserted into 'cat' is 'COAT'.
Can you help me to learn more?
(Other definitions for coat that I've seen before include "Layer of paint" , "Overgarment" , "Fleece" , "Ulster, perhaps" , "Outer garment" .)