Make an application, or joke about it, possibly (3,2)
I believe the answer is:
put in
'make an application' is the definition.
'put in' can be an answer for 'make' (thesaurus). I'm unsure of the 'an application' bit.
'joke about it possibly' is the wordplay.
'joke' becomes 'pun' (pun is a type of joke).
'about' indicates putting letters inside.
'possibly' indicates an anagram.
'it' is an anagram of 'ti'.
'pun' going around 'ti' is 'PUT-IN'.
'or' acts as a link.
Can you help me to learn more?
(Other definitions for put in that I've seen before include "Rugby throw to a set scrum" , "being asked to bat" , "Insert" , "Russian president" , "Submit" .)