Chronic complainer in great cry of pain (6)
I believe the answer is:
grouch
'chronic complainer' is the definition.
(I've seen this in another clue)
'great cry of pain' is the wordplay.
'great' becomes 'gr' (abbreviation used in place names).
'cry of pain' becomes 'ouch' (exclamation said when in pain).
'gr'+'ouch'='GROUCH'
'in' is the link.
(Other definitions for grouch that I've seen before include "Bellyache" , "Person continually grumbling" , "one known for grumbling" , "One miserable" , "Complaint" .)