After month in recession, gave angry tirade about store's termination being certain (10)
I believe the answer is:
guaranteed
'certain' is the definition.
(guaranteed can mean certain or definite)
'after month in recession gave angry tirade about store's termination' is the wordplay.
'after month' becomes 'aug' (abbreviation for August. I am not sure about the 'after' bit.).
'in recession' shows that the letters should be reversed in order (letters recede or go back).
'gave angry tirade' becomes 'ranted' (a tirade is an angry rant).
'about' indicates putting letters inside.
'termination' indicates one should take the final letters.
The final letter of 'store' is 'e'.
'aug' in reverse letter order is 'gua'.
'ranted' going around 'e' is 'ranteed'.
'gua'+'ranteed'='GUARANTEED'
'being' acts as a link.
(Other definitions for guaranteed that I've seen before include "Covered against failure" , "Supported" , "Promised" , "protected" , "Warranted" .)