Called back, finding large lump (5)
I believe the answer is:
gnarl
'lump' is the definition.
(I've seen this before)
'called back finding large' is the wordplay.
'called' becomes 'rang' ('ring' can be a synonym of 'call').
'back' says the letters should be written backwards.
'finding' says to put letters next to each other.
'large' becomes 'l'.
'rang' written backwards gives 'gnar'.
'gnar'+'l'='GNARL'
(Other definitions for gnarl that I've seen before include "Rough lump (on a tree)" , "lump of wood" , "Lump, growl" , "Tree-swelling" , "Lump or knot in a tree" .)