Lady regularly feels restricted by heart problem (8)
I believe the answer is:
angelina
'lady' is the definition.
'regularly feels restricted by heart problem' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'restricted by' is an insertion indicator (I've seen this in other clues).
'heart problem' becomes 'angina'.
The alternating letters of 'feels' are 'el'.
'el' inserted into 'angina' is 'ANGELINA'.
(Other definitions for angelina that I've seen before include "-- Jolie, US actress" , "woman" .)