Gent, sorry when falling short, working to be sturdier (8)
I believe the answer is:
stronger
'be sturdier' is the definition.
('strong' can be similar in meaning to 'sturdy')
'gent sorry when falling short working' is the wordplay.
'when falling short' means to remove the last letter.
'working' indicates an anagram.
'gent'+'sorry'='gentsorry'
'gentsorry' with its final letter removed is 'gentsorr'.
'gentsorr' anagrammed gives 'STRONGER'.
'to' is the link.
(Other definitions for stronger that I've seen before include "More potent" , "Less weak" , "More robust" , "Mightier, stouter" , "Having greater power" .)