Unusual to grab head of lizard and choke (8)
I believe the answer is:
strangle
'choke' is the definition.
(I know that strangle is a more specific form of asphyxiate)
'unusual to grab head of lizard' is the wordplay.
'unusual' becomes 'strange' (similar in meaning).
'to grab' means one lot of letters goes inside another.
'head of lizard' becomes 'l' (I can't explain this - if you can you should give a lot more credence to this answer).
'strange' enclosing 'l' is 'STRANGLE'.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for strangle that I've seen before include "Choke to death" , "gag" , "Tanglers - asphyxiate them" , "Subdue" , "Kill by squeezing the throat" .)