Watering hole of a bloodsucker seen outside Delhi regularly (8)
I believe the answer is:
alehouse
'watering hole' is the definition.
'a bloodsucker seen outside delhi regularly' is the wordplay.
'bloodsucker' becomes 'louse' (I've seen this before).
'seen outside' means one lot of letters goes inside another.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
The alternating letters of 'delhi' are 'eh'.
'louse' enclosing 'eh' is 'lehouse'.
'a'+'lehouse'='ALEHOUSE'
'of' is the link.
(Other definitions for alehouse that I've seen before include "Inn" , "drinks here?" , "Hostelry (of old)" , "old tavern" , "the nineteenth?" .)