Take two inches off for good health! (4-4)
I believe the answer is:
chin-chin
'good health' is the definition.
'take two inches off' is the wordplay.
'two inches' can mean two replacements for 'inch'.
'take' becomes 'ch' (I can't justify this - if you can you should give a lot more credence to this answer).
'inch' becomes 'in' (abbreviation).
'off' is an anagram indicator.
'inch' with letters rearranged gives 'chin'.
'ch'+'in'+'chin'='CHIN-CHIN'
'for' is the link.
Can you help me to learn more?
(Other definitions for chin-chin that I've seen before include "Cheers, bottoms up" , "good health ..." , "Down the hatch!" .)