Popular tip: take a breath! (7)
I believe the answer is:
inspire
'take a breath' is the definition.
(I've seen this before)
'popular tip' is the wordplay.
'popular' becomes 'in' ('in' can mean trendy).
'tip' becomes 'spire' (I can't explain this - if you can you should believe this answer much more).
'in'+'spire'='INSPIRE'
Can you help me to learn more?
(Other definitions for inspire that I've seen before include "Encourage - animate - draw into the lungs" , "Excite" , "Give rise to (a feeling)" , "Inhale" , "trigger" .)