Learner cheers up incongruously in vault (9)
I believe the answer is:
sepulchre
'vault' is the definition.
(I've seen this before)
'learner cheers up incongruously' is the wordplay.
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'incongruously' is an anagram indicator.
'l'+'cheers'+'up'='lcheersup'
'lcheersup' is an anagram of 'SEPULCHRE'.
'in' acts as a link.
(Other definitions for sepulchre that I've seen before include "Help curse (anag) - tomb" , "Resting place" , "vault" , "Burial place" , "An ancient tomb - whited in Gospels" .)