It can sound just the same when an H is dropped (3)
I believe the answer is:
hah
'it can sound just' is the definition.
The definition suggests a singular noun but the answer is not.
'same when an h is dropped' is the wordplay.
'same' becomes 'h' (I can't explain this - if you can you should give a lot more credence to this answer).
'when' becomes 'as' (eg 'when I walked' means 'as I walked').
'an' becomes 'i' (Roman numeral for one).
'dropped' suggests deleting specific letters (some letters are excluded or dropped).
'as'+'i'+'h'='asih'
'asih' with 'is' taken out is 'ah'.
'h'+'ah'='HAH'
'the' acts as a link.
Can you help me to learn more?
(Another definition for hah that I've seen is " Expression of surprise (one letter short of a laugh)".)