Dogged old boy's swallowed, consuming can (9)
I believe the answer is:
obstinate
'dogged' is the definition.
('obstinate' can be similar in meaning to 'dogged')
'old boy's swallowed consuming can' is the wordplay.
'old boy's' becomes 'obs' (I've seen this in other clues).
'swallowed' becomes 'ate'.
'consuming' is an insertion indicator.
'can' becomes 'tin' ('tin' can be a synonym of 'can').
'obs'+'ate'='obsate'
'obsate' enclosing 'tin' is 'OBSTINATE'.
(Other definitions for obstinate that I've seen before include "Cussed" , "Firm" , "Stubbornly persistent" , "Female bird" , "Like mules" .)