Animal runs into pipe (5)
I believe the answer is:
horse
'animal' is the definition.
(thesaurus)
'runs into pipe' is the wordplay.
'runs' becomes 'r' (cricket abbreviation).
'into' means one lot of letters goes inside another.
'pipe' becomes 'hose' (I've seen this before).
'r' going into 'hose' is 'HORSE'.
(Other definitions for horse that I've seen before include "Might one be up on this" , "Quadruped; cavalry" , "Stallion, e.g." , "Domesticated animal" , "Equine quadruped" .)