Obligatory rise in desire, receiving moving caress (9)
I believe the answer is:
necessary
'obligatory' is the definition.
(similar in meaning)
'rise in desire receiving moving caress' is the wordplay.
'rise in' is a reversal indicator.
'desire' becomes 'yen' (yen can mean a longing or desire).
'receiving' means one lot of letters goes inside another.
'moving' indicates anagramming the letters (letters are moved around).
'yen' in reverse letter order is 'ney'.
'caress' with letters rearranged gives 'cessar'.
'ney' placed around 'cessar' is 'NECESSARY'.
(Other definitions for necessary that I've seen before include "Required to be done" , "Indespensable, essential" , "Requisite" , "Inescapable" , "Required, needed" .)