Steer regularly seen around short cattle breed for this reason (9)
I believe the answer is:
therefore
'for this reason' is the definition.
(I've seen this before)
'steer regularly seen around short cattle breed' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'seen around' indicates putting letters inside.
'short' means to remove the last letter.
'cattle breed' becomes 'hereford' (breed of cattle).
The alternating letters of 'steer' are 'te'.
'hereford' with its last letter taken off is 'herefor'.
'te' going around 'herefor' is 'THEREFORE'.
(Other definitions for therefore that I've seen before include "has a triangular formation in maths?" , "Ergo" , "In consequence" , "It follows" , "Consequently - for that reason" .)