Steamship with room to change, for a change (13)
I believe the answer is:
metamorphosis
'a change' is the definition.
(metamorphosis is a kind of change)
'steamship with room to change' is the wordplay.
'with' says to put letters next to each other.
'to change' indicates anagramming the letters.
'steamship'+'room'='steamshiproom'
'steamshiproom' anagrammed gives 'METAMORPHOSIS'.
'for' acts as a link.
(Other definitions for metamorphosis that I've seen before include "Total change in form" , "Complete change of appearance" , "Transmutation" , "changing?" , "Process of transformation" .)