Nothing all right with dreadful threat around? Cheered up (4,5)

'cheered up' is the definition.
(to take heart is to be cheered by something)

'nothing all right with dreadful threat around?' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'all right' becomes 'ok' (synonyms).
'with' means one lot of letters go next to another.
'dreadful' indicates anagramming the letters.
'around?' indicates putting letters inside.
'threat' anagrammed gives 'theart'.
'o'+'ok'='ook'
'ook' going within 'theart' is 'TOOK HEART'.