Host of drugs Member of Congress will tuck into (5)
I believe the answer is:
emcee
'host' is the definition.
(I know that host can be written as emcee)
'drugs member of congress will tuck into' is the wordplay.
'drugs' becomes 'ee' (an abbreviation for ecstasy written twice).
'member' becomes 'm' (political abbreviation).
'of congress' becomes 'ce' (I can't justify this - if you can you should give a lot more credence to this answer).
'will tuck into' means one lot of letters goes inside another.
'm'+'ce'='mce'
'ee' placed around 'mce' is 'EMCEE'.
'of' is the link.
Can you help me to learn more?
(Other definitions for emcee that I've seen before include "Someone presenting" , "Master of ceremonies (mainly US)" , "I introduce speakers" , "A host of Americans" , "One presiding over an event" .)