Cook over fire, almost tough (8)
I believe the answer is:
rigorous
'tough' is the definition.
(thesaurus)
'cook over fire almost' is the wordplay.
'cook' becomes 'rig' (I've seen this in other clues).
'over' becomes 'o' (cricket abbreviation).
'fire almost' becomes 'rous' (I can't justify this - if you can you should give a lot more credence to this answer).
'rig'+'o'+'rous'='RIGOROUS'
Can you help me to learn more?
(Other definitions for rigorous that I've seen before include "Severe, precise" , "Unsparing" , "Allowing no deviation from a standard" , "Leaving no stone unturned" , "Strict as discipline may be" .)