Avoid regularly tense head (6)
I believe the answer is:
escape
'avoid' is the definition.
(escaping is a kind of avoiding)
'regularly tense head' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'head' becomes 'cape' (I've seen this before).
The alternating letters of 'tense' are 'es'.
'es'+'cape'='ESCAPE'
(Other definitions for escape that I've seen before include "issue" , "Leak; avoid" , "Get free from confinement or control" , "'Break free, get away (6)'" , "Computer key" .)