A strike leads to speculation that they'll only be successful very briefly (3-3,6)

'they'll only be successful very briefly' is the definition.
I know nothing about this answer so I cannot judge whether this works.

'a strike leads to speculation' is the wordplay.
'a' becomes 'one'.
'strike' becomes 'hit' (synonyms).
'leads to' says to put letters next to each other.
'speculation' becomes 'wonder' (I can't explain this - if you can you should give a lot more credence to this answer).
'one'+'hit'+'wonder'='ONE-HIT WONDER'

'that' is the link.

Can you help me to learn more?