Many, in the end, speak this tongue (5)
I believe the answer is:
tamil
'speak this tongue' is the definition.
'tamil' can be an answer for 'tongue' (Tamil is an example). I am not certain of the rest of the definition.
'many in the end' is the wordplay.
'many' becomes 'm'.
'in' means one lot of letters goes inside another.
'the end' becomes 'tail' (tail is a kind of end).
'm' inserted inside 'tail' is 'TAMIL'.
Can you help me to learn more?
(Other definitions for tamil that I've seen before include "South Indian people or language" , "One in race" , "Sri Lankan" , "S. India/Sri Lankan person, tongue" , "Asian language" .)