Shoemaker’s form, when visiting doctor, is desperate (4-4)
I believe the answer is:
last-gasp
'desperate' is the definition.
(I've seen this before)
'shoemaker's form when visiting doctor' is the wordplay.
'shoemaker's form' becomes 'last' (I've seen this in another clue).
'when' becomes 'as' (eg 'when I walked' means 'as I walked').
'visiting' indicates putting letters inside.
'doctor' becomes 'GP' (general practitioner).
'as' inserted into 'gp' is 'gasp'.
'last'+'gasp'='LAST-GASP'
'is' acts as a link.
(Other definitions for last-gasp that I've seen before include "Final breath or done at the last possible moment of effort" , "Finalk expiration, moment of death" , "Final exhalation before death" , "Remnant of energy or final exhalation" , "'Final breath (4,4)'" .)