Dream of fish getting swallowed (6)
I believe the answer is:
ideate
'dream' is the definition.
'fish getting swallowed' is the wordplay.
'fish' becomes 'ide' (I've seen this before**).
'getting' means one lot of letters go next to another.
'swallowed' becomes 'ate'.
'ide'+'ate'='IDEATE'
'of' is the link.
(Other definitions for ideate that I've seen before include "Form a picture of" , "Form in the imagination" , "Imagine (psychology), aid tee (anag.)" , "Fancy" .)