Frequent pursuit involving article (5)
I believe the answer is:
haunt
'frequent' is the definition.
(I've seen this before)
'pursuit involving article' is the wordplay.
'pursuit' becomes 'hunt' (synonyms).
'involving' means one lot of letters goes inside another.
'article' becomes 'a' (the indefinite article in English).
'hunt' going around 'a' is 'HAUNT'.
(Other definitions for haunt that I've seen before include "Unhat (anag.)" , "Visit in spectral form" , "Mainfest presence as ghost does" , "favourite spot" , "Regularly visit" .)