One imagines deer and ram cavorting (7)
I believe the answer is:
dreamer
'one imagines' is the definition.
(I've seen this before)
'deer and ram cavorting' is the wordplay.
'and' says to put letters next to each other.
'cavorting' indicates anagramming the letters.
'deer' put after 'ram' is 'ramdeer'.
'ramdeer' anagrammed gives 'DREAMER'.
(Other definitions for dreamer that I've seen before include "Martin Luther King" , "Gerontius" , "such an unpractical person!" , "description of an Oxford spire?" , ""You may say I'm a __" (John Lennon)" .)