No head on chicken after model gets to be more involved (7)
I believe the answer is:
thicken
'no head' is the definition.
Although both the answer and definition are verbs in their base form, I can't understand how one could define the other.
'chicken after model gets to be more involved' is the wordplay.
'chicken' becomes 'hen' (hen is a kind of chicken).
'after' says to put letters next to each other.
'model' becomes 't' (Ford Model T car).
'gets' means one lot of letters goes inside another (gets can mean captures or absorbs).
'to be more involved' becomes 'ick' (I can't explain this - if you can you should give a lot more credence to this answer).
'hen' put after 't' is 'then'.
'then' placed around 'ick' is 'THICKEN'.
'on' acts as a link.
Can you help me to learn more?
(Other definitions for thicken that I've seen before include "Make less flowing" , "Become more involved" , "Make more viscous" , "Become more viscous" , "Make dense" .)