Recalled age mother had hidden in this last letter, perhaps? (5)
I believe the answer is:
omega
'this last letter perhaps?' is the definition.
'omega' can be an answer for 'last' (I've seen this before). I'm not certain of the rest of the definition.
'recalled age mother had hidden' is the wordplay.
'OMEGA' is hidden back-to-front in amongst the letters.
But, I'm not sure how the hidden word is indicated.
'in' is the link.
Can you help me to learn more?
(Other definitions for omega that I've seen before include "Greek character symbolizing resistance" , "Ending of a series or sequence" , "24th Greek letter" , "Conclusion" , "Last letter of the Greek alphabet" .)