Salesman in ground cited as feeble (8)
I believe the answer is:
decrepit
'feeble' is the definition.
('decrepit' can be a synonym of 'feeble')
'salesman in ground cited' is the wordplay.
'salesman' becomes 'rep' (I've seen this before).
'in' is an insertion indicator.
'ground' is an anagram indicator (grind the letters ).
'cited' anagrammed gives 'decit'.
'rep' placed into 'decit' is 'DECREPIT'.
'as' acts as a link.
(Other definitions for decrepit that I've seen before include "Dilapidated, made weak by age" , "run down" , "Doddering" , "Worn out; infirm" , "In the last stages of decay" .)