When I entered, spoke low (3)
I believe the answer is:
sad
'spoke low' is the definition.
'sad' can be an answer for 'low' (I've seen this before). I am not certain of the 'spoke' bit.
'when i entered' is the wordplay.
'when' becomes 'sd' (I can't explain this - if you can you should believe this answer much more).
'i' becomes 'a'.
'entered' means one lot of letters goes inside another.
'sd' going around 'a' is 'SAD'.
Can you help me to learn more?
(Other definitions for sad that I've seen before include "Deplorable" , "Unfortunate" , "Melancholy or pitiful" , "'Unhappy, sorry (3)'" , "Mournful and depressed" .)