Can a man have clumpy sperm, ?

Clumpy sperm: Yes clumpy sperm can occur.

Yes: "clumpy" semen is a fairly common finding in men and almost always of no clinical significance especially in the absence of any symptoms. Contributing factors may include infrequent ejaculation, dehydration, diet, inflammation, and less often infection. If no symptoms of prostate inflammation or infection (pain, burning, blood in semen), then no further evaluation needed.