See fellows ditching leader being thankful? (8)
I believe the answer is:
beholden
'being thankful?' is the definition.
(thesaurus)
'see fellows ditching leader' is the wordplay.
'see' becomes 'behold' (beholding is a kind of seeing).
'fellows' becomes 'men' (fellow can mean a man).
'ditching leader' means to remove the first letter.
'men' with its initial letter taken off is 'en'.
'behold'+'en'='BEHOLDEN'
(Other definitions for beholden that I've seen before include "Bound" , "Owing thanks, indebted" , "Under an obligation" , "Owing gratitude (to)" , "Obliged" .)