Great pub's diversified, importing beers regularly (6)
I believe the answer is:
superb
'great' is the definition.
(I know that great can be written as superb)
'pub's diversified importing beers regularly' is the wordplay.
'diversified' is an anagram indicator.
'importing' is an insertion indicator.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
The alternate letters of 'beers' are 'er'.
'pubs' with letters rearranged gives 'supb'.
'supb' enclosing 'er' is 'SUPERB'.
(Other definitions for superb that I've seen before include "Surpassingly good" , "'Excellent, splendid (6)'" , "fine" , "Quite splendid, really excellent" , "Splendid, marvellous" .)