Arouse cattle - about 550 (6)
I believe the answer is:
kindle
'arouse' is the definition.
(synonyms)
'cattle about 550' is the wordplay.
'cattle' becomes 'kine' (synonyms).
'about' means one lot of letters goes inside another.
'550' becomes 'dl' (I can't justify this - if you can you should give a lot more credence to this answer).
'kine' placed around 'dl' is 'KINDLE'.
(Other definitions for kindle that I've seen before include "Inflame" , "Ignite" , "Cause to blaze" , "Make something start burning" , "Light (fire)" .)