Secreting it back among the shuffled cards is going too far (7)
I believe the answer is:
drastic
'far' is the definition.
Both the definition and answer are adjectives. Maybe you can see a link between them that I don't see?
'secreting it back among the shuffled cards is going too' is the wordplay.
'secreting' means one lot of letters goes inside another (inserted letters are hidden or secreted).
'back' says to take the final letters (the letter at the back).
'among' is an insertion indicator (inserted letters are placed among others).
'the shuffled' indicates an anagram.
'is going too' becomes 'i' (I can't justify this - if you can you should give a lot more credence to this answer).
The last letter of 'it' is 't'.
'cards' anagrammed gives 'drasc'.
'drasc' placed around 'i' is 'drasic'.
't' placed into 'drasic' is 'DRASTIC'.
Can you help me to learn more?
(Other definitions for drastic that I've seen before include "'Dramatic, extreme (7)'" , "'Severe, extreme (7)'" , "Harsh, severe" , "Extreme - violent" , "Extremely severe" .)