Old vessel one gets on, cheering (7)
I believe the answer is:
ovation
'cheering' is the definition.
(thesaurus)
'old vessel one gets on' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'vessel' becomes 'vat' (vat is a kind of vessel**).
'one' becomes 'i' (Roman numeral).
'gets' is a charade indicator (letters next to each other).
'o'+'vat'+'i'+'on'='OVATION'
(Other definitions for ovation that I've seen before include "Great reception" , "Applause, acclaim" , "Enthuiastic applause, often standing" , "Round of applause, may be standing" , "Burst of applause" .)