Simply gives us tea when out; depend upon it! (9)
I believe the answer is:
austerely
'simply' is the definition.
(thesaurus)
'us tea when out depend upon it' is the wordplay.
I cannot quite see how this works, but
'us' is found in the answer.
an anagram of 'tea' is 'ate' which is present in the remaining letters.
'when' could be 'e' (I've seen this in other clues) and 'e' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'gives' acts as a link.
Can you help me to learn more?
(Other definitions for austerely that I've seen before include "without extravagance" , "seriously" .)