Slowly cooked topside of beef brought up (7)
I believe the answer is:
braised
'slowly cooked' is the definition.
'braised' can be an answer for 'cooked' ('braised' can be similar in meaning to 'cooked'). I'm not sure about the 'slowly' bit.
'topside of beef brought up' is the wordplay.
'topside of beef' becomes 'b' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'brought up' becomes 'raised' ('raise' can be a synonym of 'bring up').
'b'+'raised'='BRAISED'
Can you help me to learn more?
(Other definitions for braised that I've seen before include "Stewed in closed pot" , "Fried then slowly stewed" .)