For example, strongly and firmly braved troubles before onset of senility (7)
I believe the answer is:
adverbs
'for example strongly and firmly' is the definition.
I can't judge whether this definition defines the answer.
'braved troubles before onset of senility' is the wordplay.
'troubles' indicates an anagram (I've seen 'troubled' mean this).
'before' means one lot of letters go next to another.
'onset of' indicates taking the first letters.
The first letter of 'senility' is 's'.
'braved' is an anagram of 'adverb'.
'adverb'+'s'='ADVERBS'
Can you help me to learn more?
(Other definitions for adverbs that I've seen before include "quickly, perhaps" , "Parts of speech" , "They qualify or modify other words" , "Modifying words" .)