Scuba, say, friend puts on in the morning (7)
I believe the answer is:
acronym
'scuba' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.
'friend puts on in the morning' is the wordplay.
'friend' becomes 'crony' (a crony is a friend or associate).
'puts on' is an insertion indicator (some letters put on or wear other letters).
'in the morning' becomes 'am' (short for ante meridiem - before noon).
'crony' inserted inside 'am' is 'ACRONYM'.
'say' is the link.
Can you help me to learn more?
(Other definitions for acronym that I've seen before include "Word like laser or Aids" , "Radar, for example" , "Mar cony (anag)" , "NATO, for example" , "Word such as radar, laser" .)