Missionary position adopted by naked men (7)
I believe the answer is:
apostle
'missionary' is the definition.
(I've seen this before)
'position adopted by naked men' is the wordplay.
'position' becomes 'post' (synonyms).
'adopted by' means one lot of letters goes inside another (I've seen this in other clues).
'naked men' becomes 'ale' (I can't justify this - if you can you should give a lot more credence to this answer).
'post' inserted into 'ale' is 'APOSTLE'.
Can you help me to learn more?
(Other definitions for apostle that I've seen before include "Peter, perhaps" , "Follower of Christ" , "Luke or John, say" , "Early Christian teacher" , "Chosen disciple" .)