Tear up Age less eagerly but with a clear head (7)
I believe the answer is:
soberly
'but with a clear head' is the definition.
I can't tell whether this defines the answer.
'tear up age less eagerly' is the wordplay.
'tear up' becomes 'sob' (I can't justify this - if you can you should believe this answer much more).
'less' is a deletion indicator.
'eagerly' with 'age' taken out is 'erly'.
'sob'+'erly'='SOBERLY'
Can you help me to learn more?
(Another definition for soberly that I've seen is " In a non-alcoholic manner.".)