Regret accepting void Portuguese currency (5)
I believe the answer is:
rupee
'currency' is the definition.
(eg currency of India)
'regret accepting void portuguese' is the wordplay.
'regret' becomes 'rue' (synonyms).
'accepting' indicates putting letters inside.
'void' suggests removing the centre (the word is empty or void of its inside letters).
'portuguese' with its middle removed is 'pe'.
'rue' placed around 'pe' is 'RUPEE'.
(Other definitions for rupee that I've seen before include "India's currency" , "foreign money" , "Indian bread" , "Currency of India, Pakistan and Bhutan" , "11 [LOLLY] in Kerala" .)