An Arab: his quatrain regularly recalled (5)
I believe the answer is:
iraqi
'an arab' is the definition.
(I've seen this before)
'his quatrain regularly recalled' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'recalled' is a reversal indicator.
'his'+'quatrain'='hisquatrain'
The alternate letters of 'hisquatrain' are 'iqari'.
'iqari' in reverse letter order is 'IRAQI'.
(Other definitions for iraqi that I've seen before include "Probably a Muslim" , "Someone from Baghdad, for example" , "Baghdadi, perhaps" , "Native of Baghdad, say" , "Citizen of Baghdad, say" .)