Josh bores porter perhaps with single complaint (8)
I believe the answer is:
beriberi
'single complaint' is the definition.
'beriberi' can be an answer for 'complaint' (beriberi is a kind of disease). I am not certain of the 'single' bit.
'josh bores porter perhaps' is the wordplay.
'josh' becomes 'rib' (I've seen this in another clue).
'bores' indicates putting letters inside (bore can mean to drill into).
'porter' becomes 'beer' (I've seen this in other clues).
'perhaps' becomes 'i' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'rib' inserted inside 'beer' is 'beriber'.
'beriber'+'i'='BERIBERI'
'with' is the link.
Can you help me to learn more?
(Other definitions for beriberi that I've seen before include "Tropical disease affecting nerves" , "Asian disease caused by a dietary deficiency" , "Disease caused by vitamin B deficiency -- ie briber (anag)" , "Disease (lack of vit. B1)" , "illness" .)